For an organic light-emitting diode (OLED) display panel, usually a back plate including a driving thin film transistor (TFT) with a top-gate structure is adopted. In the case that a light beam from an OLED reaches an active layer of the driving TFT, drift may occur for a threshold voltage of the driving TFT. Hence, a property of the driving TFT may change significantly and thereby a display effect of the OLED display panel may be adversely affected.